1. Field of the Invention
The present invention relates to a magnesium alloy material and a production process thereof, and more particularly, to a magnesium alloy material having high mechanical strength and a production process thereof.
2. Description of the Related Art
In general, since magnesium alloy materials have the lowest density and lightest weight among practically used alloys while also having high strength, they are being increasingly used in applications such as chassis of electrical products as well as automobile wheels, underbody parts and around-the-engine parts.
Since parts used in automobile-related applications are particularly required to have high mechanical properties, materials of specific shapes are produced by a single roll process or rapid solidification process using magnesium alloy materials to which elements such as Gd or Zn have been added (see, for example, Japanese Patent Application Laid-open No. H06-041701, Japanese Patent Application Laid-open No. 2002-256370, and Michiaki Yamasaki and three others. “Novel Mg—Zn—Gd Alloys in which a long period stacking ordered Structure is Formed by High-Temperature Heat Treatment”, Summary of Presentations at the 108th Spring Conference (2005) of the Japan Institute of Light Metals, Japan Institute of Light Metals, 2005, p. 43-44).
However, although the above-mentioned magnesium alloy materials allow the obtaining of high mechanical properties in specific production processes, these production processes have a disadvantage of requiring special equipment and having low productivity, while also having a problem of the existence of limitations on those members that can be used practically.
Therefore, processes have been proposed that allow the obtaining of magnesium alloy materials having practically useful mechanical properties even if plastic forming (extrusion) is carried out from ordinary dissolving and casting having high productivity without using special equipment or processes as indicated in the above-mentioned publications in the case of producing magnesium alloy materials (see, for example, International Publication Nos. WO 2005/052204, WO 2005/052203 and WO 2006/036033 and Japanese Patent Application Laid-open No. 2006-97037). The magnesium alloy materials disclosed in these publications have a long period stacking ordered structure within their structure and are known to allow the obtaining of high mechanical properties.